Use Of Plastic
Waste In Rural Road
Construction

Plastic being a cheap material, is used in many applications and it
has now become part of our everyday life style. Steady use of
plastics has led to the increase in the amount of plastic waste
being generated in India. These wastes as part of municipal waste are
randomly dumped on the outskirts of a city, occupying vast land areas,
which otherwise can be used for other purposes of welfare of society.

Fig. 1: Plastic Waste Dumped in Open Land

Fig. 2: Burning of Plastic is a Health hazard

This discarded waste plastic is consumed by animals and birds resulting
in their death. Flood-like situations are often created in metropolitan
cities due to clogging of drainage with plastic wastes. It also leads to
ground water pollution and global warming. It is estimated that more
than 15,000-tonne of plastic waste is generated in India, out of which
9,000 ton is collected and processed, whereas, remaining plastic waste
is not collected. Disposal of plastic waste materials through land filling
or incineration is not effective as it further pollutes the environment
by generating toxic gases and due to chances of fire at landfill site.

Plastic is a non-biodegradable material and researchers have
found that the material can remain on earth for 4,500 years without
degradation. Several studies have proved the health hazard caused by
improper disposal of plastic waste (Fig. 2).
Depending on physical properties, plastic waste is classified as
thermoplastic and thermosetting material. Thermoplastic materials can
be formed into desired shapes under heat and pressure and become
solids on cooling. This cooled plastic can be remoulded to any shape
and size when subjected to the same conditions of heat and pressure.
Thermosetting materials on the other hand, cannot be softened or
remoulded by the application of heat. Most of thermoplastics soften
when heated to a temperature of 130-140°C and they do not produce
any gas in the temperature range of 130-180°C. This property makes
them very suitable for blending with bitumen as the process for road
construction using bitumen is carried out in the range of 155-165°C.
Thermoplastic constitutes almost 80 per cent of total waste plastic
generated in India and therefore their use in road construction can
alleviate the problem of their disposal and ground pollution very
effectively.

Prof. Satish Chandra
Director
CSIR-CRRI
New Delhi

Process of Utilization
There are three different possible processes to incorporate waste
plastic into bituminous mixes.
Dry Process: In this process, the waste plastic is added to hot
aggregates to get Plastic Coated Aggregates (PCA). Optimum quantity
of bitumen is then added to produce waste plastic modified bitumen mix
WPMB-MIX. A 1-3mm particle size of waste plastic in shredded or powder
form is preferable for commercial production of mix and field trials have
successfully been completed in India in several Metro cities including
Bengaluru, Chennai, Kerala, Tamilnadu and Delhi since 2002.Wet Process: Waste Plastic along with other additive is melted
and stirred in hot bitumen at around 150°C using a high shear
mixer to produce WPMB, which is then added to hot aggregates to
produce Modified Bituminous Mix. The process has been patented
by Central Road Research Institute, Delhi but the process is yet to be
commercialized. Field trials are also required to validate the process.Semi Wet Process: Waste plastic is miscible in bituminous phase
in hot melt condition and gets separated from bituminous phase on
cooling. But, some of the plastics in the mixed waste stream do not
melt completely and remains dispersed despite adding additives as
during recycling process plastics are toughened with colourant dyes
and other fillers, chemical and inert additives. Partially Modified
Bitumen containing undisclosed waste plastic particles is then used to
coat the hot aggregates to produce Waste Plastic Modified Bituminous
Mixes. The undisclosed plastic acts as a cushion aggregate in modified
mixes at ambient temperature to service temperature. This process is
preferred over wet process to have the dual benefit of plastic waste
i.e. as a modifier to bitumen and as a cushion for better interlocking of
aggregates. This process is also under validation.
The total quantity of waste plastic used in all the three applications
is 8-12 per cent by weight of bitumen.Codal Provisions
Based on the laboratory studies and field performance inputs
from various researchers, National Rural Roads Development Agency
(NRRDA), Ministry of Rural Development, Government of India,
has formulated guidelines for the use of plastic waste in rural roads
construction. The guidelines say that the performance studies carried
out on the roads (using waste plastic) constructed in Tamil Nadu
indicated “satisfactory performance with good skid resistance, good
texture value, stronger and less amount of progressive unevenness
over a period”. The experiments conducted at CRRI also indicated
better performance of the mix containing waste plastic. The guidelines
recommend the use of poly films with thickness up to 60 micron,
hard and soft foams and laminated polymer with thickness of up to
60 microns. However, poly vinyl chloride sheets (flex sheets) are not
for their use in bituminous mixes. The process of coating
aggregate with molten (waste) plastic does not require any machinery
and no toxic gases evolve in the process. It is recommended that the
percentage of shredded waste plastic will be 8% for blending the
bitumen in the construction of plastic roads.

Dr. Sangita
Senior Principal Scientist
CSIR-CRRI
New Delhi

Indian Roads Congress has also published “Guidelines for the Use
of Waste Plastic in Hot Bituminous Mixes (Dry Process) in Wearing
Courses”, vide IRC SP-98 2013, which clearly indicate the use of plastic
waste in dense and open graded mixes. Type of waste plastic and its
source, advantages, limitations and design of mixes of using waste plastic
in road construction are covered in these guidelines. Open graded mixes
like premixing surfacing and mixed seal are still in practice in rural roads.Advantages of Plastic Roads
A well-constructed Plastic Tar Road will result in the following
advantages as given in the NRRDA guidelines for use of waste plastic
in road construction.
- Strength of the road increased (Increased Marshall Stability Value)
- Better resistance to water and water stagnation
- No stripping and have no potholes.
- Increased binding and better bonding of the mix.
- Increased load withstanding property (Withstanding increased load
transport)
- Overall consumption of bitumen decreases.
- Reduction in pores in aggregate and hence less rutting and ravelling.
- Better soundness property.
- Maintenance cost of the road is almost nil.
- The Road life period is substantially increased.
- No leaching of plastics.
- No effect of radiation like Ultra violet (UV) rays.
The process is easy to execute. All the plastic gets collected and sent
to a place where it is shredded into fine pieces, making it convenient to
use. The pieces are then mixed into a mixture of bituminous concrete or
tar. Both the elements are heated at high temperature before mixing.
Contrary to popular belief, using plastic is cheaper too. Therefore, if the
plastic waste is properly channelized in road development across the
country, the civic bodies can make roads, which are cheaper and durable.Applications in Field
In 2015, the Indian government made it mandatory to incorporate
plastic waste in the construction of roads. More than 1,600-tonne of
plastic has been used to lay over 1,000-km of roads in Tamil Nadu in
the last five years as part of the government’s thrust on effective use
of plastic waste. Maharashtra state authorities have already tied up with
one agency for building twelve trial plastic roads across the city of Pune.
The city of Indore is already recycling half of its plastic waste on daily
basis, where 30% is being used in roads. So far, more than 500 km of
roads have been constructed. Two kilometres of bituminous concrete

Fig. 3: Road in Delhi Made with waste Plastic

Fig. 4: Road in Bangalore Made with Waste Plastic

Fig. 5: Road Made Using Waste Plastic in Jamshedpur

overlay were laid on Road No.43 in Delhi in 2007 also and later on several
other roads like Sarita Vihar T-Point to Okhla Barrage, Kalka Temple to
ESI Hospital road, Sachivalaya Road, etc.
A 25-km road with waste plastic was laid in Bangalore. The plastic
road performed better than conventional road laid at the same time,
which began developing “crocodile cracks” after few months of its
laying (Fig. 4). In 2007-08, bituminous concrete overlay containing
waste plastic was laid on 3.6 km length of road in Delhi under the
supervision of CRRI.
Jamshedpur is the only city in eastern India where an environmentfriendly
technology with incorporation of waste plastic into bituminous
mix (Dry Process) has been implemented using accumulated waste
plastic of the city (Fig. 5). Jamshedpur Utility and Services Company
(JUSCO) has constructed 12-15 km roads in the steel city, as well
as widened 22 roads by way of using waste plastic, including biscuit
packets, poly bags, etc. It has been reported that for every one-km
long and four-metre-wide road one ton of bitumen will be saved if this
technology is adopted.Conclusion
The use of recycled waste plastic in pavement asphalt represents
a valuable outlet for such materials. The use of modified bitumen with
the addition of processed waste plastic of about 5-10% by weight of
bitumen helps in substantially improving the strength, fatigue life and
other desirable properties of bituminous concrete mixes. It also reduces
the consumption of bitumen. Plastic coating on aggregates provides
better binding with bitumen due to increased bonding and increased area
of contact between polymers and bitumen. The polymer coating also
reduces the voids. This prevents the moisture absorption and oxidation of
bitumen by entrapped air. The roads can withstand heavy traffic and show
better durability as there is reduction in water absorption. The process is
easy to execute and does not require any modification to the plant. The
plastic roads made from recycled materials are not only greener but are
also stronger and economical. It is an earnest step to reduce the plastic
waste. Using it to lay roads is the most viable solution.

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